The present invention relates to a method of sharing a three-dimensional virtual reality space, a system of sharing a three-dimensional virtual reality space, a method of information processing, an information recording medium, a method of information recording, an information transmission medium, a method of information transmission, a client terminal, and a shared server terminal and, more particularly, to the above-mentioned methods, systems, media, and terminals that can provide a three-dimensional virtual reality system to many and unspecified users on a worldwide scale for example.
A cyberspace service named Habitat (trademark) is known in the so-called personal computer communications services such as NIFTY-Serve (trademark) of Japan and CompuServe (trademark) of the US in which a plurality of users connect their personal computers via modems and public telephone network to the host computers installed at the centers of the services to access them in predetermined protocols. Development of Habitat started in 1985 by Lucas Film of the US, operated by Quantum Link, one of the US commercial networks, for about three years. Then, Habitat started its service in NIFTY-Serve as Fujitsu Habitat (trademark) in February 1990. In Habitat, users can send their alter egos called avatars (the incarnation of a god figuring in the Hindu mythology) into a virtual city called Populopolis drawn by two-dimensional graphics to have a chat (namely, a real time conversation based on text entered and displayed) with each other. For further details of Habitat, refer to the Japanese translation of "Cyberspace: First Steps," Michael Benedikt, ed., 1991, MIT Press Cambridge, MA, ISBN0-262-02327-X, the translation being published Mar. 20, 1994, by NTT Publishing, ISBN4-87188-265-9C0010, pp. 282-307.
Now, referring to FIGS. 35-37, an example of the constitution of a related art cyberspace system, which is provided by personal computer communications services, represented by above-mentioned Habitat is shown.
In the figure, a server terminal 1 has a storage device 2 to supply image data stored therein to client terminals 3-1 through 3-3 via a public telephone network 4.
Each of the client terminals 3-1 through 3-3 specifies, as a symbol representing the user of that terminal in a virtual three-dimensional space, a predetermined one of a plurality of avatars stored in the storage device 2 in advance. The user can move the specified avatar in the three-dimensional virtual reality space provided by the server terminal 1 to enjoy a virtual experience of living a life in that space.
For example, the client terminal 3-1 accesses the server terminal 1 via the incorporated modem and the public telephone network 4 to receive an image of the virtual reality space. When, in the client terminal 3-1, a specific operation is performed to instruct its own avatar (for example, avatar A) to move in a specified direction, an image corresponding to the moving direction comes from the server terminal 1. This allows the client terminal 3-1 to move its own avatar through a town provided by the virtual reality space.
In the client terminal 3-2, too, its own avatar (for example, avatar B) may be specified in the same manner as mentioned above to move around in the virtual reality space.
If avatar A of the client terminal 3-1 and avatar B of the client terminal 3-2 have moved to positions closely facing each other in the virtual reality space, the server 1 provides not only the image of the town providing the background but also the image of avatar B moving around the town. This allows the client terminal 3-1 to display an image as shown in FIG. 36 for example. Namely, its own avatar A is located at the center of the screen with avatar B of the client terminal 3-2 located in its proximity.
Likewise, on the client terminal 3-2, an image as shown in FIG. 37 is provided. Namely, its own avatar B is located at the center of the screen with avatar A of the client terminal 3-1 located in its proximity.
Further, when, in the client terminal 3-3, its own avatar (for example, avatar C) is set to move the same in the proximity of avatar A and avatar B in the virtual reality space, an image in which avatars A through C are arranged is provided to the client terminals 3-1 through 3-3.
Thus, a change (for example, a change of avatar location or attribute or creation of a new object) added by any of the client terminals (3-1 through 3-3) to the virtual reality space is provided to the other client terminals, thereby implementing the sharing of the same virtual reality space among the users (namely, clients) of the client terminals 3-1 through 3-3.
The related art cyberspace system represented by above-mentioned Habitat operated in the above-mentioned personal communications services has a multi-user capability in which a plurality of users share the same virtual reality space displayed in two-dimensional graphics via the client terminals 3-1 through 3-3 to share the movement and the like of avatars of these users.
However, the related art multi-user capability is restricted to only specified users, not open to unspecified users. Namely, taking the above-mentioned Habitat for example, users are required first to purchase dedicated personal computer communications software, install the software program in their own personal computers (the client terminals 3-1 through 3-3), connect the personal computers to the host computer (the server terminal 1) via the modem and the public telephone network 4, and register themselves as members of Habitat by online sign-up. Only after the registration, can they access the virtual reality space. Therefore, the virtual reality space is available only to the registered members, excluding the unspecified users.
Moreover, in the related art cyberspace system represented by Habitat, a virtual street, a virtual room interior, and the like are drawn in two-dimensional graphics. In such an environment, movement of an avatar backward or forward is realized simply by moving it up or down in a two-dimensional background, providing poor representation for enabling the user to experience walking or movement in the virtual space. Because this scheme makes the user look at the virtual space in which the user's avatar and another user's avatar are shown from the viewpoint of a third person, the sense of the pseudo experience is marred to a large extent. Therefore, realization of the walk-through capability has been awaited by the industry concerned, in which the virtual space is displayed in three-dimensional graphics and a user can walk freely in the virtual space from the viewpoint of an avatar, thus enhancing the sense of the pseudo experience.
On the other hand, for a related art example for realizing the sharing of a three-dimensional virtual reality space on a network, a system of FIG. 38 is known which is constituted by client terminals 3-5 through 3-7 interconnected by the LAN (Local Area Network) installed in companies or laboratories.
First, all client terminals 3-5 through 3-7 read graphics data that describe the same three-dimensional space to display the same three-dimensional space. At this point of time, the three-dimensional spaces visually recognized by all users match each other.
Meanwhile, if, at a client terminal 3-5, the user changed positions of his avatar A from the position indicated by a dashed line to the position indicated by a solid line as shown in FIG. 38 for example, information about the change (or change information) is sent to client terminals 3-6 and 3-7 via a LAN, not shown. Then, based on the change information from the client terminal 3-5, display is changed at the client terminals 3-6 and 3-7.
Namely, as shown in FIG. 38, the change information about the positional change of avatar A at the client terminal 3-5 (in the example of FIG. 38, "Move Object to (10,20,30)") is sent to the client terminals 3-6 and 3-7, at which display of avatar A is changed from the position indicated by dashed line to the position indicated by solid line according to the change information. Thus, avatar A moved at the client terminal 3-5 is also moved at the client terminals 3-6 and 3-7.
Likewise, if a change is made to the virtual reality space at the client terminal 3-6 or 3-7 other than the client terminal 3-5, the change is reflected at the other client terminals, thus allowing the users of all client terminals to share the same virtual reality space.
It should be noted that an object representing an avatar, or an alter ego of a user, can be moved in the virtual reality space, entered in it, and made to exit from it; in other words, the avatar is changed in its states or the states are updated. So, such an object is appropriately called an update object hereinafter. On the other hand, an object representative of a building constituting a town in the virtual reality space is used commonly by a plurality of users and does not change in its basic state. Even if the building object changes, it changes autonomously, namely it changes independent of the operations made at client terminals. Such an object commonly used by a plurality of users is appropriately called a basic object hereinafter.
Meanwhile, it will be convenient if a shared virtual reality space such as mentioned above can be offered to not only specified users but also many and unspecified users on a worldwide scale.
In the related art cyberspace system such as Habitat operated by a personal computer communications service as shown in FIG. 35, access to the server terminal 1 is enabled by offering a telephone number for the online sign-up. However, unless the membership registration is made, no non-member users can share the two-dimensional virtual reality space, thus making the system unavailable to the unspecified users.
Further, since the accesses of all users concentrate on the same host computer (the server terminal 1), the number of users that can access the host computer at a time is limited. And as the number of users increases, the throughput of the host computer must be enhanced accordingly, requiring maintenance such as update of the system and server software.
In addition, the system of FIG. 38 constituted via the LAN is unavailable to unspecified users accessing from outside companies or laboratories. If the change information about objects such as avatars is transferred in a communication protocol shown in FIG. 38, it is required to know beforehand the destination addresses of client terminals 3-5 through 3-7 of the users who share the three-dimensional virtual reality space. Therefore, although it is possible for the specified users, it is impossible for the unspecified users to obtain the addresses of the client terminals of all other others before hand to set the obtained addresses to their client terminals.